[Intel-gfx] drm/i915: don't change DRM configuration when releasing load detect pipe

[Jesse Barnes]

On Mon, 08 Mar 2010 21:59:29 +0100
Brice Goglin <Brice.Goglin at gmail.com> wrote:

> Eric Anholt wrote:
> > On Thu, 18 Feb 2010 14:51:54 -0800, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> >   
> >> When we get a CRTC to use for load detection, we restore its DPMS state
> >> if needed.  We shouldn't, however, change the DRM configuration by
> >> calling drm_helper_disable_unused_functions when we release the CRTC.
> >> Doing so can cause problems with resume, since at suspend or lid close
> >> time, X may choose to probe outputs.  If it doesn't re-probe them at
> >> open or resume time, LVDS won't be restored, since
> >> drm_helper_disable_unused_functions will have turned it off, preventing
> >> the mode set at lid open from restoring it.
> >>     
> >
> > It seems to me like the bug is that drm_helper_disable_unused_functions
> > whacks the configuration.  Why should it do that?
> >
> > 		if (connector->status == connector_status_disconnected)
> > 			connector->encoder = NULL;
> >
> > This function back in UMS used to be about getting the system from
> > unknown bootup state to other junk being turned off after the initial
> > modeset (which was of course broken, since having the other junk turned
> > on during modeset could break things, so really it should have been
> > intel_turn_everything_off_thanks() before doing a modeset).
> >
> > Once that's fixed, it seems like it'd be a replacement for the
> > turn-off-after-load-detect logic in the load detect pipe release
> > function.
> >   
> 
> Did anything get applied to fix this issue in the end ? Jesse's initial
> patch fixed blank screens on my i 945 so I am still applying it to my
> kernels for now.

Arg, totally dropped this one.

Dave, please comment on the above.

-- 
Jesse Barnes, Intel Open Source Technology Center